Try scraping the glue areas. Sanding is futile. The tape glue heats and spreads and thinner will disolve it and stain the wood deep into the grain.

You can scrape with a single edge razor or any of the vast array of scrapers available. I like a cabinet scraper for that. It's a piece of hardened steel about business card size. Any piece of steel can be filed to a flat edge and be used.

It sounds like the boat got darker due to dust and dirt and the tape blocked that. A scraping of the tape areas folowed with a light sanding would have probable done it. If you already did damage by using solvent, you may have to live with that or try scraping down a bit further. See how deep it goes or if you can get rid of it.

When you pile strips on top of strips with carpenters glue you'll run into the similar problem. Wherever the top strip is blended to the lower you expose the glue line. You can never get rid of it since it travels under all of the wood. That's where epoxy should have been used rather than carpenters glue. You'll have to fake and live with that best you can. Once again - use a scraper not sand paper.

Best of luck - we all make mistakes - be creative as you can.